engine starts but dies after a few seconds

1994 JEEP GRAND CHEROKEE
223,000 MILES • 6 CYL • 4WD • AUTOMATIC
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PLOCO
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Hi guys. I have a 1994 Jeep grand cherokee laredo 4x4 6cyl. I just recently bought this jeep it ran then it wouldnt start then ran fine again. I did a tune up of plug wires, plugs, cap, rotor, coil, pick up coil, crank sensor. It ran fine for a day and wouldnt start after that. Fuel pump works and great pressure. Relays are all good and the same with the fuses. It would crank over but no spark to the coil. Then we found a used ignition control module {brain box} from the same yr. model and options mine has for $35.00 and not $650.00 new. Now it starts up but dies a few seconds after like I turned the key off. Still good fuel pressure and relays. It has a security system but I dont know how it works. Im kinda lost now. Any ideas??? Thanks guys!!!
Nov 19, 2010 at 3:14 AM
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JACOBANDNICKOLAS
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Have you checked the crank sensor? Also, is it an aftermarket alarm? I don't recall a factory alarm came with them in 94. Let me know.

Joe
Nov 19, 2010 at 3:20 AM
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PLOCO
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i replaced the crank sensor. also there is an aftermarket alarm installed. i tryed turning switches off an then starting jeep but still doing the same.
Nov 19, 2010 at 2:11 PM
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PLOCO
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Maybe the asd relay? I swapped relays but the same starts up but dies after a few seconds. Anybody got any ideas? lol. Thanks.
Nov 20, 2010 at 1:14 PM
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JACOBANDNICKOLAS
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This is a tough one with an aftermarket alarm. God knows what one it is. Have you been able to check to see if spark is being lost to kill the engine or fuel pressure? I realize it shows good at first, but one is killing the engine after a few seconds.

As far as the ASD, if it was bad, the vehicle wouldn't start at all.
Nov 20, 2010 at 7:04 PM
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PLOCO
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The fuel is good but the spark cuts out just after start up.
Nov 20, 2010 at 8:40 PM
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JACOBANDNICKOLAS
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No knowing what kind of an alarm system you have, can you tell how to disconnect it?
Nov 20, 2010 at 9:50 PM
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